The present invention relates to substrate processing method and apparatus for processing a surface to be processed of a substrate with a processing liquid. More particularly, the present invention relates to a substrate processing method and apparatus suitable for use in a coating process for forming a thin film on a substrate or in an etching process for thinly removing the surface of a substrate in semiconductor manufacturing processes.
In semiconductor device manufacturing processes, various processing operations using processing liquids are performed on substrate surfaces to be processed. In such a case, it is necessary to uniformly supply processing liquids to the processing surface of the substrate. For example, to coat a substrate surface with a resist uniformly and to uniformly effect development after exposure, it is necessary that processing liquids used in the resist coating process and the developing process be supplied uniformly to the substrate surface. In the developing process in particular, the development processing area per unit area of the substrate varies from place to place to a considerable extent, depending on the exposure pattern (i.e. in a region where the development area is large, the concentration of the developing solution is likely to be reduced, while in a region where the development area is small, the concentration of the developing solution is likely to be increased, resulting in a large difference in concentration from region to region). Therefore, it is difficult to carry out development processing uniformly.
In view of the above-described problem, an object of the present invention is to provide substrate processing method and apparatus capable of uniformly supplying a processing liquid having a uniform concentration to a substrate surface in substrate processing such as development processing without affecting the physical properties of the processing liquid and without damaging the substrate.
To attain the above-described object, the present invention provides substrate processing method and apparatus for processing a surface of a substrate with a processing liquid. The substrate is placed horizontally, and a rotating blade is disposed above the substrate so as to face it. The processing liquid is supplied to the surface of the substrate, and the rotating blade is rotated while being kept out of contact with the processing liquid to induce a gas current over the processing liquid. The gas current forms a mass of processing liquid having a surface current and an internal circulating current on the surface of the substrate.
As stated above, the rotating blade disposed to face the substrate is rotated while being kept out of contact with the processing liquid, thereby inducing a gas current over the processing liquid. The gas current forms a mass of processing liquid having a surface current on the substrate surface below the rotating blade. The surface current induces an internal circulating current in the mass of processing liquid. As a result, the processing liquid can be supplied uniformly to the substrate surface by the internal circulating current. Furthermore, because the processing liquid is stirred by the internal circulating current, it is possible to dissolve a concentration difference in the processing liquid that occurs as the processing progresses and hence it is possible to uniformize the concentration. In addition, because the substrate is placed in a stationary state and the rotating blade rotates out of contact with the processing liquid, the substrate is not shocked or stressed. Accordingly, there is no likelihood of the substrate being damaged.
Preferably, the rotating shaft of the rotating blade and the rotor of a motor for driving the rotating blade are supported with magnetic bearings.
When the rotating shaft of the rotating blade and the rotor of the motor for driving the rotating blade are supported in a magnetic levitation manner with magnetic bearings, there is no possibility that the substrate or the processing space will be contaminated with particles or the like that would otherwise be generated by friction.
The substrate processing method or apparatus may include a step or device for moving the rotating blade in parallel to the substrate.
By moving the rotating blade parallel to the substrate, the gas current induced by the rotating blade also moves along with the movement of the rotating blade, therefore, the mass of processing liquid formed by the gas current on the substrate surface below the rotating blade also moves on the substrate surface as the rotating blade moves. Therefore, even a large-sized substrate can be uniformly processed over the whole surface thereof.
Preferably, the rotating blade is a planar disk.
The rotating blade in the shape of a planar disk makes it easy to form a mass of processing liquid having an internal circulating current on the substrate surface below the rotating blade. That is, the rotating blade in the shape of planer disk does not form any downward gas current toward the substrate, which makes the formation of the gas current from the substrate toward the rotating blade easy; thus, the formation of the mass of processing liquid is also made easy.
The above and other objects, features and advantages of the present invention will become more apparent from the following description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings.